Awesome gift. Yes, use the counter weight, although you can get along without it for chicken. Set the weight opposite the breast, adjust it in or out as needed to balance. You can get an idea of the balance just by holding the spit loosely in you hands. Put a full lit basket on each side, start spinning and start checking temps after about an hour. It will be good.
You don't have to wait for a weekend, though. Cook whatever for dinner, and start a chicken after that is done. Or fire two kettles. Just set a timer for an hour and a quarter or whatever to go check temps and take the chicken off. Then the chicken is ready for the next night's meal - chicken, chicken enchiladas, chicken tacos, chicken soup, chicken sandwiches, chicken and pasta...